Hemophagocytic lymphohistiocytosis is characterized by massive lymphocyte and macrophage activation and proliferation. When observed in association with juvenile idiopathic arthritis it is also called "macrophage activation syndrome" being a potentially lethal complication of this disease. We report the case of a 26 years old woman with juvenile idiopathic arthritis (polyarthritis, rheumatoid factor negative) since 13 years old, receiving nonsteroidal anti-inflammatory drugs (diclofenac, nimesulide). She was admitted with systemic inflammatory response, fever, lymph node enlargement, splenomegaly, anemia, thrombocytopenia, hypofibrinogenemia, hyperferritinemia, hypertriglyceridemia and bone marrow hemophagocytosis. Aspects related to pathogenesis, diagnosis and treatment of this little known disease are discussed.
macrophage activation syndrome; hemophagocytic lymnphohistiocytosis; juvenile idiopathic arthritis
